P403: PROGNOSTIC SIGNIFICANCE OF LONG NON-CODING RNA GAS5 AND MICRORNA-222 EXPRESSION PROFILES IN YOUNGER AML PATIENTS
Authors: Ð. Pavlović, N. Tošić, B. Zukić, I. Marjanović, Z. Pravdić, N. Suvajdžić Vuković, S. Pavlović, V. Gašić
Journal: HemaSphere (2022)

Background: Acute myeloid leukemia (AML) is a heterogeneous malignant disease, that accounts for 80% of all acute leukemias in adults. The treatment protocol and prognosis for AML are based on the classification of the patients into risk groups based on the pretreatment karyotype analysis. However, nearly half of the patients don’t have any detectable cytogenetic changes. Therefore, there is a constant need to find new prognostic markers, as well as markers that can be used as targets for therapeutics that could improve the treatment. Recently, using high-throughput technologies, the search for new biomarkers has pointed towards non-coding RNAs, especially long non-coding RNAs (lncRNAs) and micro RNAs (miRNAs). Numerous studies have shown lncRNA GAS5 expression level dysregulation in multiple cancers, but it was poorly investigated in AML. Additionally, miR-222 expression levels have shown significant influence on cancers in general, including AML. Since GAS5 acts like a molecular sponge for miR-222, co-expression profiles of these non-coding RNAs could be novel prognostic markers in AML. Aims: We have investigated the expression level pattern of lncRNA GAS5 in younger AML patients and examined its potential influence on disease outcome. GAS5 expression levels were also investigated in AML patients with normal karyotype, while taking into account miR-222 expression levels, in order to examine their potential role as dual biomarkers. Methods:: 94 bone marrow samples of younger (<65 years) AML patients have been collected. Diagnostics and stratification were based on cytomorphology, immunophenotyping and cytogenetic analysis. All patients received the same induction chemotherapy. Along with them, 14 healthy controls were analysed. The AML patient group with normal karyotype (AML-NK) had 39 patients. GAS5 and miR-222 expression levels were analysed using Real-Time PCR. Relative quantification was performed using the ddCt method, respective healthy controls were used as the calibrator for each non-coding RNA. The ROC curve analyses found the optimal cut-off value to discriminate between Gas5high and GAS5low. While the cut-off value for dividing miR-222 expression levels into miR-222high and miR-222low was performed using the value of the median level of expression among healthy controls. Results: Our results showed that GAS5 expression level in AML patients was lower compared to healthy controls (p < 0.01). Lower GAS5 expression on diagnosis was related to an adverse prognosis, since higher levels of lactate dehydrogenase was detected in the GAS5low group compared to the GAS5high group (p < 0.01). The disease-free survival (DFS) and the overall survival (OS) were significantly lower in the GAS5low group, compared to the GAS5high group, but survival analysis failed to confirm this finding. In the AML-NK group patients had higher expression of miR-222 compared to healthy controls (p < 0.01). A synergistic effect of GAS5low/miR-222high status on disease prognosis was not established. Summary/Conclusion: This is the first study focused on examining the lncRNA GAS5 and miR-222 expression pattern in AML patients. Its initial findings indicate potential prognostic significance of GAS5 expression and the need for further investigation of these two non-coding RNAs, their potential roles in leukemogenesis, and the prognosis of AML patients.